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From: Paul Brook <paul@codesourcery.com>
Date: Sat, 10 Nov 2007 14:53:59 +0000
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Message-Id: <200711101454.01251.paul@codesourcery.com>
Subject: [Qemu-devel] mips64 gdbstub broken
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To: Thiemo Seufer <ths@networkno.de>
Cc: qemu-devel@nongnu.org

A recent CVS commit ("Fix gdb stub for MIPS64.") looks incorrect:

> diff -u -r1.66 -r1.67
> --- gdbstub.c   8 Oct 2007 13:16:14 -0000       1.66
> +++ gdbstub.c   25 Oct 2007 21:30:37 -0000      1.67
> @@ -563,7 +563,7 @@
>          ptr += sizeof(target_ulong);
>        }
>
> -    *(target_ulong *)ptr = tswapl(env->CP0_Status);
> +    *(target_ulong *)ptr = (int32_t)tswap32(env->CP0_Status);
>      ptr += sizeof(target_ulong);

This is obviously bogus. The new value sent to gdb will depend on the host 
endianness. 

I suspect what you meant to do is

  *(target_ulong *)ptr = tswapl((int32_t)env->CP0_Status);

i.e. sign extended to a target-endian 64-bit value. This is consistent with 
the implementation of cpu_gdb_write_registers.

Could you confirm?

Paul